Research Findings: In this research, 487 Chinese children age 3 to 5 years took part in a number line estimation task. This task was used to assess children's estimation accuracy and their estimation patterns along a number line in two different estimation circumstances. Situation A had the same line lengths for different numeric ranges, whereas situation B held the ratio of line lengths to numeric ranges constant. There were also three different number ranges (1-5/10/20). A new mathematical modeling method was proposed, where the two-dimensional estimation patterns of one child would be modeled as points in a higher dimensional space. Then the Dirichlet process Gaussian mixture model was applied to dynamically estimate the number of classes and assemble the different points into discrete classes based on distance. Three conclusions were drawn as follows: (a) significant differences were found within children for different ages and number ranges; (b) Chinese preschoolers had more estimation patterns than just linear pattern and logarithmic pattern, especially in small number ranges; and (c) mental number distance played an important role in their estimation patterns. Practice or Policy: Implications for early mathematic instruction on children's understanding of mental number line are discussed.